Implementations of the claimed invention generally may relate to schemes for enhancing image or video information and, more particularly, to schemes for enhancing the contrast of image or video information.
Pictures in video sequences may include three signals (e.g., red/green/blue (RGB) or luminance and chrominance (YUV) sampled in both the horizontal and vertical directions. For those images in the YUV color space, contrast may be conceptualized as a feature that indicates distribution of energy among different luminance (Y) values in an image. In general, contrast enhancement may increase the dynamic range of an image, while redistributing the energy in the image to the extremes (e.g., the highest and the lowest) of the luminance values.
The sharpness of an image may be a perceptual impression that is based on a concentration of relatively high energy in the high frequency components of an image. Some contrast enhancement may enhance the details in an image, also resulting in an increase in perceived sharpness.
Too much contrast enhancement, however, may result in the loss of fine details in an image, and a corresponding reduction in sharpness, because energy may be redistributed within luminance values of an image without balancing or tracking the effect of such redistribution on the high frequency components of the image.